Sub‐lethal effects of deltamethrin residues on the within‐crop behaviour and distribution of Coccinella septempunctata

Abstract

The behaviour and distribution of adult Coccinella septempunctata L. (Coleoptera: Coccinellidae) were recorded in two plots of winter wheat infested with the cereal aphids Sitobion avenae (E) and Metopolophium dirhodum (Walk.) (Homoptera: Aphididae). One plot was sprayed with the pyrethroid insecticide deltamethrin at a rate of 6.25 g a.i./ha and the other was left unsprayed. Single ladybird beetles were released sequentially on the ground at the centre of the sprayed and unsprayed plots and their behaviour and position in the crop canopy were recorded at 30 second intervals for a total of 15 min per beetle. Assessments, with fresh beetles, continued for four days after spray application with a total of eighty ladybird beetles observed. The 15 min period was selected to avoid lethal effects and no ladybird beetles were killed or knocked down as a result of exposure to deltamethrin residues during this period. Significant differences were found between the overall behaviour patterns of C. septempunctata in the untreated and deltamethrin treated plots up to three days after the spray application. Ladybird beetles exposed to deltamethrin residues were observed to walk and groom significantly more frequently and to rest significantly less frequently than those in the unsprayed plot. Significant differences were also found between the observed distribution of ladybird beetles in the sprayed and unsprayed crop canopies, with higher numbers of observations towards the bottom of the crop canopy and on the ground in the deltamethrin treated plot than in the untreated plot during the first two days after deltamethrin application. Upon the foliage itself, ladybird beetles were observed significantly more frequently on the abaxial leaf surface in the deltamethrin treated crop compared with the untreated crop. The results are discussed in terms of possible evidence for the repellency of deltamethrin to C. septempunctata and also the implications for integrated pest management of changes in predator behaviour and crop distribution resulting from sub-lethal uptake of insecticides.

Disruptive Sublethal Effects of Insecticides on Biological Control: Altered Foraging Ability and Life Span of a Parasitoid after Feeding on Extrafloral Nectar of Cotton Treated with Systemic Insecticides

“…The latter finding suggests that odors from some insecticidetreated plants may invoke avoidance behavior in beneficial insects that can potentially modify their effectiveness as biological control agents. Similar findings on insecticide-induced avoidance behavior were reported by Gu De Jiu and Waage (1990) and Umoru et al (1996) in the aphid parasitoid Diaeretiella rapae M'Intosh and by Wiles and Jepson (1994) in Coccinella septempunctata L. In these studies, the behavioral effects were likely caused by both contact experience with the insecticide and insecticide odor. The question then arises whether avoidance behavior in the field will prevent M. croceipes from being exposed to the three insecticides that we examined in our study.…”

Effect of synthetic insecticides on the larvae of Coccinella septempunctata from Greek populations

“…Walking and grooming were more intense, resting was lower, distribution was toward the lower part of the canopy and the ground as compared to the untreated. This behavior was attributed to possible repellent activity of the insecticide (Wilis and Jepson 1994). A similar walking behavior away from the release point in field was observed in imidacloprid sprayed adults of C. septempunctata compared to water sprayed insects (Banks and Stark 2011).…”

Spatial Heterogeneity and Insect Adaptation to Toxins

“…Under these conditions, the importance of fitness effects associated with physiological tolerance (e.g. 134,135) and of predators (165), parasitoids (95), and pathogens (63, 96) would have to be considered, both for their contribution to plant protection and selection of both behavioral and physiological traits.…”